Digital creep and drift correction

Abstract

Sensor apparatus for determining a deformation due to creep in an output of a sensor, said sensor apparatus comprising force means arranged for applying a mechanical force to said sensor, said sensor arranged for measuring, in a current measurement, a displacement of said sensor caused by said applied force and a processor component arranged for determining said deformation due to creep for a next measurement by said sensor.

1 . A sensor apparatus for determining a deformation due to creep in an output of a sensor, said sensor apparatus comprising:
 force means arranged for applying a mechanical force to said sensor;   said sensor arranged for measuring, in a current measurement, a displacement of said sensor caused by said applied force;   a processor component arranged for determining said deformation due to creep for a next measurement by said sensor, by:
 providing a creep function, wherein said creep function defines said deformation due to creep over time; 
 calculating said deformation due to creep for a next measurement, based on: 
 said creep function; 
 a time between:
 said current measurement of said sensor and 
 said next measurement;
 wherein said time between said current and said next measurement is a small portion of an overall measurement time; 
 
 
 said measured applied force in said current measurement; 
 a deformation due to creep in said current measurement. 
   
     
     
         2 . The sensor apparatus for determining a deformation due to creep according to  claim 1 , wherein said overall measurement time is continuous. 
     
     
         3 . The sensor apparatus for determining a deformation due to creep according to  claim 1 , said sensor apparatus comprising:
 calibrating means arranged for:
 applying a predetermined mechanical force to said sensor; 
 measuring, by said sensor, said applied force over time; 
 determining and providing, by said processor component, said creep function based on a direct relation between said predetermined mechanical force and said measured applied force over time. 
   
     
     
         4 . The sensor apparatus according to  claim 1 , wherein said creep function is an exponential function. 
     
     
         5 . The sensor apparatus according to  claim 1 , wherein said processor component is further arranged for:
 initially determining said deformation due to creep for a first measurement by said sensor component by:
 providing said creep function, wherein said creep function defines said deformation due to creep over time; 
 a time between:
 a start of said applying said mechanical force to said sensor, and 
 said first measurement by said sensor. 
 
   
     
     
         6 . The sensor apparatus according to  claim 1 , wherein said sensor is further arranged for measuring, in said next measurement, said applied force, wherein said sensor apparatus further comprises:
 correcting means arranged for correcting said measured applied force by taking into account said calculated deformation due to creep.   
     
     
         7 . A sensor apparatus for determining an applied mechanical force using an output of a sensor which is measuring said applied mechanical force in which said sensor is exposed to a drifting error, said sensor apparatus comprising a sensor and a processor component, wherein said sensor apparatus is arranged for:
 measuring, in a first measurement, by said sensor of said sensor apparatus, said applied force when no force is applied;   nulling, by a processor component comprised by said sensor apparatus, said measured applied force in said first measurement;   applying a mechanical force to said sensor;   measuring, in a second measurement, by said sensor by said sensor apparatus, said applied force;   stop applying said mechanical force to said sensor;   measuring, in a third measurement, by said sensor, said applied force when no force is applied to said sensor;   nulling, by said processor component, said measured applied force in said third measurement, therewith obtaining a drifting error that occurred between said first and third measurement;   correcting said second measurement by an interpolated value, said interpolated value being provided by interpolating, by said processor component, the obtained drifting error between said first measurement and said third measurement for said second measurement.   
     
     
         8 . The sensor apparatus for determining an applied mechanical force to a sensor according to  claim 7 , wherein said processor component is arranged for linearly interpolating between said first measurement and said third measurement. 
     
     
         9 . A bond tester apparatus for determining a deformation due to creep in testing a strength of a bond and/or a material, said bond tester apparatus comprising a sensor apparatus according to  claim 1 . 
     
     
         10 . A method of determining a deformation due to creep in an output of a sensor, comprised by a sensor apparatus, which sensor is measuring a mechanical force, said method comprising the steps of:
 applying a mechanical force to said sensor;   measuring, in a current measurement, by said sensor, a displacement of said sensor caused by said applied force;   determining, by a processor component comprised by said sensor apparatus, said deformation due to creep for a next measurement by said sensor, by:
 providing a creep function, wherein said creep function defines said deformation due to creep over time; 
 calculating said deformation due to creep for a next measurement, based on:
 said creep function; 
 a time between:
 said current measurement of said sensor, and 
 said next measurement; 
 wherein said time between said current and said next measurement is a small portion of an overall measurement time; 
 
 said measured applied force in said current measurement; 
 a deformation due to creep in said current measurement. 
 
   
     
     
         11 . The method of determining a deformation due to creep according to  claim 10 , wherein said overall measurement time is continuous. 
     
     
         12 . The method of determining a deformation due to creep according to  claim 10 , wherein said step of providing said creep function comprises:
 applying, to said sensor, a predetermined mechanical force;   measuring, by said sensor, said applied force over time;   determining and providing, by said processor component, said creep function based on a direct relation between said predetermined mechanical force and said measured applied force over time.   
     
     
         13 . The method for determining a deformation due to creep according to  claim 10 , wherein said creep function is an exponential function. 
     
     
         14 . The method for determining a deformation due to creep according to wherein said method further comprises the initial steps of:
 determining, by said processor component, said deformation due to creep for a first measurement by said sensor by:
 providing said creep function, wherein said creep function defines said deformation due to creep over time; 
 a time between:
 a start of said applying said mechanical force to said sensor, and 
 said first measurement by said sensor. 
 
   
     
     
         15 . The method of determining a deformation due to creep according to  claim 14 , wherein said creep function is dependent on said mechanical force applied at said start. 
     
     
         16 . The method of determining a deformation due to creep according to  claim 15 , wherein said creep function is directly proportionally dependent on said mechanical force applied at said start. 
     
     
         17 . The method of determining a deformation due to creep according to  claim 10 , wherein said method further comprises the steps of:
 measuring, in said next measurement, by said sensor, said applied force;   correcting said measured applied force by taking into account said calculated deformation due to creep.   
     
     
         18 . A method for determining an applied mechanical force using an output of a sensor which is measuring said applied mechanical force and in which is said sensor is exposed to a drifting error, said method being performed by a sensor apparatus, said method comprising the subsequent steps of:
 measuring, in a first measurement, by said sensor of said sensor apparatus, said applied force when no force is applied;   nulling, by a processor component comprised by said sensor apparatus, said measured applied force in said first measurement;   applying a mechanical force to said sensor;   measuring, in a second measurement, by said sensor by said sensor apparatus, said applied force;   stop applying said mechanical force to said sensor;   measuring, in a third measurement, by said sensor, said applied force when no force is applied to said sensor;   nulling, by said processor component, said measured applied force in said third measurement, therewith obtaining a drifting error that occurred between said first and third measurement;   correcting said second measurement by an interpolated value, said interpolated value being provided by interpolating, by said processor component, the obtained drifting error between said first measurement and said third measurement for said second measurement.   
     
     
         19 . The method for determining an applied mechanical force according to  claim 18 , wherein said step of interpolating comprises:
 linearly interpolating between said first measurement and said third measurement.   
     
     
         20 . The method according to  claim 10 , wherein said method is performed by a bond tester apparatus for determining a strength of a bond and/or a material.